a. Field of the Art
The present invention relates to improvements in a hydropneumatic gun for setting blind-rivet nuts used for integrally securing, for example, two panels to each other with a nut, and more particularly to improvements in its maneuverability. The present invention can be utilized in the field of production technology of such tools.
b. Prior Art
An electric gun for setting blind-rivet nuts is known and is generally used in the following way. A nut having an internal thread in the inner periphery of a flanged sleeve is inserted and fitted in, for example, mounting holes in two panels connected to each other, and a screw mandrel of the electric gun is threadedly connected to the nut. While pressing the flange of the nut to the lateral sides of the panel mounting holes, the screw mandrel is retracted toward the inner side of the gun body to outwardly expand and deform the nut sleeve. Thus, the two panels are secured to each other as pressed and held between the deformed sleeve and the flange (for example, Japanese Patent Publication No. 53-4674).
The screw mandrel for deforming the nut is first rotated forward for threadedly mounting the nut on the screw mandrel, and then pulled, without being rotated, in order to deform the nut, and then rotated reversely, causing the screw mandrel to be separated from the nut secured to panels or the like. These operations must to be automatically and sequentially carried out simultaneously with the securing of the nut to panels or the like. Therefore, it is very important to assure smooth power transmission and changeover for such operations. It is also important that these operations are securely carried out corresponding to the respective steps of securing the nut to panels or the like.